1. Field of the Invention
The present invention relates to a CAD/CAM apparatus for generating on a display screen a geometric shape of an object to be machined in an interactive manner with the display screen thereby generating NC data for machining the shape.
2. Description of the Prior Art
FIG. 1 is a structural drawing showing a CAD/CAM apparatus using a prior art method disclosed in, for example, Japanese Laid-open Patent Publication No. 62-214405. Referring to the figure, reference numeral 1 denotes an input unit such as keyboard, mouse, and tablet, 2 denotes a CPU for performing various processes, 3 denotes an output unit such as CRT, printer, plotter, puncher, and disk, 4 denotes a geometric shape generation portion for defining and editing geometric elements such as straight lines, circles, and curves on the display screen in an interactive manner for generating a geometric shape as an object of machining, 53 denotes a machining starting point input portion for inputting a machining starting point, 54 denotes a machining direction input portion to input a direction along which machining is advanced from the machining starting point, 9 denotes a geometric data memory for storing geometric data generated in the geometric shape generation portion 4, and 55 denotes an NC data generation portion for generating NC data from the geometric data, machining starting point information, and the machining direction information.
Operation of the apparatus will be described below FIG. 7(a) is an example of a shape of an object to be machined generated by the geometric shape generation portion 4. The shape as the object of machining is given a machining starting point a by the machining starting point input portion 53 as shown in FIG. 2(a). Then, by inputting, for example, "up" as a direction along which the machining is advanced from the machining starting point, the machining direction is input. Then, the NC data generation portion 55 generates the path from the machining starting point to the shape and, tracing the shape, outputs NC data [FIG. 2(b)].
We now consider the case to machine a plurality of different shapes as shown in FIGS. 3(a) and 3(b) under different machining conditions. Since it is not possible to assign the machining conditions such as machining speeds in association with the individual shapes, the machining starting point and machining direction are specified as described above for the shape a after the shapes have been generated, and then, after machining conditions are specified for the shape, the NC data is produced therefor. Then after machining conditions suitable for the shape b have been specified, the machining starting point and machining direction as described above are specified for the shape b and, thus, the NC data therefor is produced.
As another prior art example of the described type of CAD/CAM apparatus, there is one as shown in FIG. 4. Referring to the figure, reference numeral 1a denotes a keyboard, 2a denotes a mouse, and 3a denotes a tablet constituting the input unit for inputting geometric information and character data Reference numeral 4a denotes a geometric shape generation portion converting the geometric information into information in the format to be internally stored, 41a denotes a machining method input portion for inputting machining information, 6a denotes a geometric shape memory for storing the geometric information, 9a denotes a shape analysis portion, 11a denotes an NC information generation portion, and 12a denotes a machining path display portion, of which the NC information generation portion 11a and the machining path display portion 12a are the portions finally outputting an NC program and a machining path diagram.
Operation according to the above described arrangement will be described below. First, geometric information is input through the input unit such as the keyboard 1a, mouse 2a, and tablet 3a. The geometric shape generation portion 4a converts the input geometric information into information adapted to the internal storage format This information is stored in the geometric shape memory 6a. Further, characters input by the operator through the machining method input portion 41a are converted into machining information and stored in the geometric shape memory 6a in parallel with the geometric information. The geometric shape analysis portion 9a generates machining path information for generating the NC program from the information stored in the geometric shape memory 6a. The NC information generation portion 11a provides the machining path information with other NC information, thereby outputting the NC program, and in the meantime, the machining path display portion converts the machining path information into a set of graphic information and displays it on a CRT as a display portion 14a.
Since prior art CAD/CAM apparatuses are configured as described above, in the case of the first prior art example, for example, if the object to be machined has a plural kinds of shapes to be machined, it is impossible to assign or store the machining conditions or the like in association with every shape of the object. Therefore, when the machining condition must be changed for each shape, the machining condition must be assigned every time, that is, the processes for establishing the machining conditions and generating NC data have had to be repeated for every shape. Thus, there has been a problem that the efficiency of NC programming has been low. Further, specification of a machining method such as tapering for a specific portion of the shape has not been achievable by the operator in an interactive manner with a display screen.
In the case of the second prior art example, assignment of the machining information has been possible only to the whole of the produced set of geometric information. Therefore, when such an NC program is wanted in which a portion of the geometric information is to be machined under a different machining condition from that under which another portion is machined, there has been a problem that the definition of the geometric shape must be made by dividing the shape into two different shapes. Hence, the greater the number of the shapes and the types of the machining, the more remarkably low was the efficiency of NC programming.